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Ingy döt Net 2023-07-01 11:58:00 -04:00
parent 7387c8f97b
commit cb5bb5e222
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Task/Elliptic-curve-arithmetic/Perl/elliptic-curve-arithmetic.pl Normal file
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package EC;
{
our ($A, $B) = (0, 7);
package EC::Point;
sub new { my $class = shift; bless [ @_ ], $class }
sub zero { bless [], shift }
sub x { shift->[0] }; sub y { shift->[1] };
sub double {
my $self = shift;
return $self unless @$self;
my $L = (3 * $self->x**2) / (2*$self->y);
my $x = $L**2 - 2*$self->x;
bless [ $x, $L * ($self->x - $x) - $self->y ], ref $self;
}
use overload
'==' => sub { my ($p, $q) = @_; $p->x == $q->x and $p->y == $q->y },
'+' => sub {
my ($p, $q) = @_;
return $p->double if $p == $q;
return $p unless @$q;
return $q unless @$p;
my $slope = ($q->y - $p->y) / ($q->x - $p->x);
my $x = $slope**2 - $p->x - $q->x;
bless [ $x, $slope * ($p->x - $x) - $p->y ], ref $p;
},
q{""} => sub {
my $self = shift;
return @$self
? sprintf "EC-point at x=%f, y=%f", @$self
: 'EC point at infinite';
}
}
package Test;
my $p = +EC::Point->new(-($EC::B - 1)**(1/3), 1);
my $q = +EC::Point->new(-($EC::B - 4)**(1/3), 2);
my $s = $p + $q, "\n";
print "$_\n" for $p, $q, $s;
print "check alignment... ";
print abs(($q->x - $p->x)*(-$s->y - $p->y) - ($q->y - $p->y)*($s->x - $p->x)) < 0.001
? "ok" : "wrong";